1. Field
The present disclosure generally relates to portable medical devices which consist of physiological parameter detection devices having two or more electrodes incorporated therein.
2. Background
Atrial fibrillation (AF) is a cardiac arrhythmia, i.e. an altered electrical activity (irregular or faster or slower than normal) of the heart, that involves the atria, and is an example of one type of cardiac rhythm that would benefit from remote monitoring. AF may be detected as irregularities when taking a pulse. Rhythm disturbances i.e. arrhythmias are common, and often asymptomatic so called “silent” which at times may be life threatening. Accurate detection and diagnosis is warranted as well as monitoring. AF is the most common form of arrhythmia affecting approximately 3-5% of people over 65 and 8% of people over 80. For example, there are about 2.2 million cases in the U.S. yearly. It is a highly prevalent disease associated with significant cardiovascular morbidity and mortality. AF represents 34% of hospitalizations in the U.S. for arrhythmias annually. It is estimated that the annual cost to the U.S. Medicare system alone is more than $15.7 billion due to cost complications. However, screening and diagnosis is limited in the Medicare population. By 2015, it is projected that 15 million Americans will suffer from AF and its adverse consequences.
In AF, the electrical impulses that are normally generated by the sinoatrial node (the sinus node) are replaced by disorganized activity in the atria, leading to irregular conduction of impulses to the ventricles that generate the heartbeat. This results in irregular heartbeats. AF may be continuous (persistent or permanent AF) or alternating between periods of normal heart rhythm (paroxysmal AF). Over time, the natural tendency of AF is to become continuous/chronic. The type of AF considered to be most dangerous is paroxysmal AF because the recurrent onsets and offsets of fibrillation increase the probability of embolization significantly. During an AF episode, the blood is rather stationary in the atria and coagulation forming blood clots may take place. When the activity then returns to normal, the clots are propelled out into the cardiovascular system, potentially causing strokes etc. Further, paroxysmal AF is the type of AF that normally occurs first, i.e. it is rather unusual that a healthy subject immediately enters chronic AF. AF is a rhythm disturbance having many etiologies (causes) which include, for example, high blood pressure, diabetes, heart failure, etc. In particular AF is a common complication of heart failure. On the other hand AF in the long run may also cause or precipitate heart failure, therefore a timely detection and management is critical.
It should also be noted that out-patients with AF typically also have heart disease (about 65%). More alarmingly, though, is that AF is also associated with silent stroke, dementia and Alzheimer's disease. Stroke affects about 795,000 people annually in the U.S. (about 1 stroke every 40 seconds) and is the third leading cause of death and the number one cause of disability.
There remains a need for an improved device and method for early and convenient detection of AF and for portable and convenient devices capable of monitoring a cardiac rhythm.
Other concepts relating to the disclosure are disclosed in, for example, U.S. Pat. No. 3,565,694 to Chireau for Bipolar Electrode and Method of Making Same; U.S. Pat. No. 4,564,433 to Werdecker et al. for Bipolar Electrode; U.S. Pat. No. 6,416,471 B1 to Kumar et al. for Portable Remote Patient Telemonitoring System; U.S. Patent Publication US 2003/0110613 A1 to Ross for Screen Protector; and U.S. Patent Publication US 2003/0129355 A1 to Ross for Screen Protector.